Vehicles, people or robots that operate in environments where no a priori map is available often must construct a map in order to function and adapt to their working environment, or to provide accurate models for an end user. Mapping and localization, including simultaneous localisation and mapping (SLAM), are fundamental problems in mobile robotics, and include scenarios in which a moving object with no known map or accurate measure of its pose must estimate and maintain both.
The pose of an object refers to its position and orientation in space. Accurate knowledge of the pose of moving objects is often important for mobile tasks such as robot navigation, mapping, and planning. In particular, it is well known that in some environments conventional navigation systems cannot operate or are not practical. For example, in environments such as inside buildings, in underground mines, or in deep water, satellite-based global positioning system (GPS) technologies and cellular-based positioning technologies are often inoperative. If a detailed map of such an environment is not available, vehicles, people or robots operating in the environment may need to rely on alternative navigations systems, such as SLAM systems, which may include inertial measurement units (IMUs) or other sensors to determine position and orientation.
3D scanning beam systems can provide data for mapping and/or localization applications. Generally, such systems include an active, powered linkage mechanism that moves a sensor in multiple degrees of freedom, effectively increasing the field of view of the sensor, to obtain a 3D scan. For example some systems may include a laser ranging apparatus that outputs a one dimensional beam. If the ranging apparatus is mounted to a powered multiple-degree-of-freedom linkage or powered gimbal mechanism, the laser can be repetitively swept through a three dimensional space, such as a space in front of a vehicle. Data collected from the apparatus then can be used to define a 3D “point cloud”, which effectively defines an image or map of an environment. Other ranging apparatus can include two dimensional laser scanners that are rotated about a central axis, or moved in a third dimension when fixed to a vehicle, to define a 3D point cloud. Further, 3D flash light detection and ranging (LIDAR) apparatuses can incorporate multiple detectors in parallel to generate 3D ranging data.
In many cases 3D scanning beam systems are rigidly mounted to a vehicle or robot, and continuously scan a particular region relative to an orientation of the vehicle or robot. Collected data then can be used for mapping and/or localization applications or more basic object detection and scene awareness purposes. However, in some circumstances errors can be introduced to a rigidly mounted scanning beam system due to vibrations or jouncing of a vehicle or robot to which the system is attached. Therefore complex vibration isolation and stabilisation systems have been devised to effectively isolate 3D scanning beam systems from unwanted vibrations or movement.
In some applications the required hardware necessary to increase the field of view of a scanning sensor to effectively scan a three dimensional region can be prohibitively complex and expensive. Therefore, there is a need for an improved 3D scanning beam and imaging system.